On the Impact of PA-Induced In-Band Distortion in Massive MIMO

Conventional downlink signals in massive MIMO suffer from high PAR, which requires the power amplifiers of the base station to be backed off to avoid signal distortion, which lowers power efficiency. To improve efficiency, there are precoding schemes that produce signals with low PAR. To compare different precoding schemes, this article estimates their power consumptions through simulations, in which in-band distortion and amplifier efficiency effects are taken into consideration. It is found that, when only in-band distortion and the data rate requirement determine the back-off, the inband distortion is negligible and the power amplifiers can be operated at peak efficiency. It also turns out that low-PAR and conventional, high-PAR, precoding schemes consume approximately the same amount of power when the out-of-band part of the distortion is disregarded.